Wheel dresser for gear grinding machines



Nov. 30,1943. c. KNOWLES VETAL 2,335,341

WHEEL DRESSER FOR GEAR GRINDING MACHINES Filed Aug. 1, 1942 2Sheets-Sheet 1 lllllllllllll INVENTOR CKnoa/Zes ATTORNEY Patented Nov.30,

2,335,341 wnnm. DRESSER ron dnsncnmnmo monmns Carroll Knowles, WestHartford, and Arthur L.

Wilder, Wethersfleld, Comm, assignors to Niles- Bement-Pond Company,West Hartford, Conn, a corporation of New Jersey Application August 1,1942, Serial No. 453,226

Claims. (Cl 125-11) This invention relates to wheel dressing devices andparticularly to a wheel dressing or truing device for application togear tooth grinders.

A primary object of the present invention is to provide means to dressthe central peripheral portions of a bevelled grinding wheel to asmooth,

continuous, non-circular contour merging into the opp sitely bevelledside surfaces so that the clearance surface between the roots ofadjacent teeth-of a gear may be ground simultaneously with the flanks ofthe gear teeth and the entire surface of the gear spaces finished to asmooth, continuous surface from one tooth to the next.

One feature that enables us to accomplish the above object is that thedressing device includes two obliquely movable dressing tools preferablymounted for slidable movements on supporting bars, these bars beingpositioned to pass their diamonds over and dress the bevelled surfacesof the wheel at predetermined oblique angles to each other, and therebeing a supplementary oscillatory dressing tool mounted upon one end ofa lever pivotally mounted intermediate its length adjacent the slidabledressing tools so that as this supplementary dressing tool is oscillatedwith its lever the lever may tilt or swing about an intermediate point,the swinging movement of the lever about this pivotal point beingcontrolled by a suitable template engaged by the end of the leveropposite the dressing tool and serving to traverse the dressing tool ina continuous curve of generally arcuate form disposed centrally betweenthe paths of motion of the slidable dressing tools.

Another object of the invention is to mount the oscillatory levercarrying the supplementary dressing tool upon a central anti-frictionbearing having a spherical bearing surface upon which the lever maypivot so that during the oscillatory movements of this dressing tool itmay swing about the center of this spherical supporting surface.

And finally it is an object of the invention to control the oscillatorymovements of this supplementary dressing tool in timed relation to thereciprocatory movements of the slidably mounted dressing tools and tocontrol the pivotal movements of the supplementary tool in predeterminedadjustable curved paths determined by the adjustment of the oscillatorydressing tool and the form of the template,

With the above and other objects in view, the invention may includethefeatures of constructicn and operation set forth in thefcllowingspecification and illustrated in the acompanying drawings.

In the accompanying drawings annexed hereto and forming a part of thisspecification, we have shown the invention embodied in a dressing devicegenerally similar to that shown and described in the patent to TannerNo. 2,086,750, granted July 13, 1937, but it will be understood that theinvention can be otherwise embodied and that the drawings are not to beconstrued as defining or limiting the scope of the invention, the claimsappended to this specification being relied upon for that purpose.

In the drawings:

Figure 1 is a front elevation, partly in section,

of a dressing device for gear grinders in which the present invention isincorporated.

Fig. 2 is a side elevation in section showing the oscillatory dressingattachment and its mounting and actuating mechanism.

Fig. 3 is an end view of the lever carrying the oscillating and pivotingdressing tool showing its actuating connections.

Figs. 4 and 5 are diagrammatic views showing different relativepositions of the obliquely slidable dressing tools and the oscillatingdressing tool assumed during their dressing operation upon agrindingwheel.

Fig. 6 is a diagrammatic view on an enlarged scale showing the curvedform of the central peripheral portions of a grinding wheel and atemplate outline for producing this curve, and

Fig. 7 is a modified form of adjustable holder for the oscillatorydressing tool.

In the above-mentioned drawings there has been shown but one completeembodiment of the invention which is now deemed preferable, but it is tobe understood that changes and modifications may be made within thescope of the appended claims without departing from the spirit of theinvention.

Briefly, and in its preferred aspect, the invention may include thefollowing principal parts; First, a dressing head mounted upon orforming a part of a gear grinding machine adapted to operate upon atooth curve generating principle; second, two oppositely disposeddressing tools mounted upon suitable slidable members and manuallyactuatedin adjustable oblique direc tions through suitable operatingconnections; third, a supplementary dressing tool mounted foroscillatory movement between the slidable dressing tools upon one end ofa lever free to tilt or pivot about an intermediate point; fourth, atemplate controlling the tilting movement of the lever; during itsoscillatory movement: and

fifth, means to adjust the position of this tool 7 at predetermineddistances radially from the axis of oscillation of the lever.

In grinding gears upon the involute generating principle, it has beenthe practice to dress the sides of a single bevelled grinding wheel toappropriate conical angles. The angle at which these sides are bevelledmay vary but they are usually dressed along straight lines and at equalangles to the central plane of the wheel. These bevelled side portionsof the wheel effect the grinding of adjacent sides of adjacent teeth. Atpresent the central peripheral portion of the wheel disposed between theopposed bevelled side surfaces is usually dressed off by a special toolto form a narrow cylindrical surface intersecting the opposed bevelledsurfaces of the wheel at sharp angles. v

The present invention provides means to traverse a dressing tool overthe central peripheral portion of the wheel in a smooth, continuouscurve of 'modified'arcuate form intersecting the bevelled side surfacesat widely obtuse angles so that clearance portions between the teeth atthe bottom of the tooth spaces may be ground over their entire areasimultaneously with and to form a continuous curve with the flanks ofthe gear teeth.

Referring more in detail to the figures of the drawings, we provide asuitable housing ill for a complete dressing device for the bevelledwheel W of a gear grinder in which there are provided oppositelydisposed slidably mounted bars 52 having dressing tools it upon theirlower ends. By

suitable connections similar to those shown in the above-referred topatent, these members it are reciprocated so that their dressing toolsit are moved over the opposed bevelled surfaces of the wheel W. Theconnections for actuating these dressing tools are such that when one ofthe dressing tools i3 is at its lowermost position the opposite dressingtool is at its uppermost position.

Also actuated from the same driving connections for the slidable bars i2which may include a manually rotatable shaft id is an oscillatingdressing tool it disposed intermediate the positions of the slidabledressing tools it. This dressing tool is is adapted, as shown in thefigures, to dress the central peripheral surface of the wheel betweenthe opposed bevelled portions of th wheel. As shown most clearly in Fig.2, this oscillatory dressing device has its dressing tool mounted uponone end of a lever it. Preferably the dressing tool comprises a diamondi5 inserted in the lower end of the adjustable holdler ll positionedwithin the forward end of this lever 66. As shown in Fig. 2 thisdressing tool i5 is disposed substantially in alinement with the axis ofoscillation of the lever. Locating means for the tool 65 are indicatedin Fig. 2 to position the tool at any desired but limited distanceradially from the axis of the lever.

In order to support this lever it for oscillatory and tilting movementsthere is provided an intermediate anti-fi'iction bearing l8 having aspheri cally formed bearing surface upon its outer race so that thelever l6 may, in addition to its oscil-' erably upon anti-frictionbearings within the housing i0 and having a' bevelgear 20 mountedthereon drivingly connected to one of the driving connection for theslidably mounted dressing tools l3. This sleeve l9 surrounds the leveri6 at its end remote from the dressing tool 85, there being a largeenough opening within the sleeve to permit limited swinging movements ofthe lever about the center of bearing l8. To connect the sleeve l9 andlever i6 so that they will oscillate together while permitting the leverto swing, the rear end of the lever It has formed thereon an extension24 having fiat parallel sides which en- 1 gage opposed parallel surfaceson the end portions of the sleeve I9 which is slotted for that purpose.

.To'limit the swinging or pivotal movement of the dressing tool l5 aboutits supporting bearing 88 there is provided a suitable template 2!secured rigidly to the casing surrounding the sleeve 59 and having astud 22 passing radially through the sleeve., The form of the templatesurface is determined by the form of surface to be generated at thecentral periphery of the wheel and may be ofthe form shown upon anenlarged scale in Fig. 6. The outer end of the stud 22 engages thetemplate surface 2| and the inner end of the stud presses against thesurface of the lever IS. A compression spring 23 housed within the leverforces the lever laterally against the stud 22 and in turn presses thestud 22 against its template 2|.

In operation, by rotating the shaft carrying the worm M by the handlever 9 shown in Fig. 1, the slides 52 and their dressing tools 53 arereciprocated over the bevelled side surfaces of the wheel W.Simultaneously, through the driving connections for these slides i2 andthe bevel gear 20 the sleeve l9 surrounding the rear end of theoscillatory lever I6 is actuated. The movement or this dressing tool itand lever Hi imparted to them by the sleeve 69 is an oscillatory one,and as the dressing tool i3 is disposed a limited but adjustabledistance from the axis of the lever or member it, limited oscillatorymovement is induced to the dressing tool i5 by this movement. However,simultaneously with the oscillatory movement of the lever it it ispivotally moved about the center of its central supporting bearing l8 bymeans of the template 2| so that the dressing tool i5 traces a smoothbut non-circular curve determined by the outline of the template 2| andby its radial distance from the axis of lever l6. Essentially the curvetraced out by the dressing tool [5 is generally arcuate, dependent uponthe radial distance of the tool from the axis of lever l6 modifledslightly by the conformation of the template outline 2I.- This curve issuch that the central dressing tool l5 at the opposite ends of itsmovement blends or merges into the path of movement of the slidably'mounted dressing tools to form a continuation therewith. The entireactive surface of the grinding wheel is therefore dressed to a smoothand predetermined conformation. The clearance surface at the root of thetooth flanks between adjacent gear teeth is therefore finish-ground atthe same time the involute tooth surfaces are ground.

To adjust the position of the dresser E5 toward and from the axis ofoscillation of the lever l6, gage blocks of the required distance may beinserted between the dresser and a surface of a bracket mountable on theouter end of the lever. As shown in Fig. 2, the bracket 25 is removableand has its surface upon which the gage block is placed in alinementwith the axis of oscillation of-the lever I6.

In Fig. "I there is shown a holder for the dressing tool l that permitsadjustment laterally as well as radially of the dressing tool.Commercial diamonds vary over such a wide range of shapes and sizes thatthe holder to accom modate these variations is made adjustable. As shownin this figure the dressing tool end of the lever I6 is provided with aplane surface end against which is mounted a diamond holding block 26adapted to'slide vertically in a suitable slideway and be held inadjusted position by a screw 2'1. The block 26 carries an adjustingscrew 28 by means of which the vertical position of the block 26 may bedetermined. The block 26 also carries a bushing 29 having a holeextending vertically therethrough disposed eccentrically of the axis ofthe bushing. Within the hole in the bushing 29 is the dressing tool 30mounted within the end of a spindle 32 extending through the eccentric'hole. This spindle 32 and tool 30 may be held in their uppermostposition by a nut 33 threaded on the upper end of the spindle. Byrotation of the bushing. 29 the diamond cutting point l5 of the dressingtool 30 may be adjusted laterally so that its point will be in alinementwith the axis of the lever 16.

A screw 3i servesto clamp the bushing in ad-' justed rotative position.

We claim:

1. A dressing device for grinding wheels comprising in combination, anelongated member having a dressing tool mounted at one end, means tooscillate said member about its longitudinal axis, a supporting bearingfor said member intermediate its length about which said member mayoscillate and pivot, and template means to control the pivotal movementthereof about said bearing.

2. A dressing device for grinding wheels comprising in combination, anelongated member having a dressing tool mounted at one end foradjustment radially toward and from the axis of said member, means tooscillate said member about its longitudinal axis, a supporting bearingfor said member intermediate its length about whichsaid member mayoscillate and pivot. and template means to control the pivotal movementthereof about said bearing.

3. A dressing device for grinding wheels comprising in combination, an,elongated member having a dressing tool mounted at one end. means toposition said dressing tool at predetermined adjustable distances fromthe axis of said member. means to oscillate said member about itslongitudinal axis, a supporting bearing for said member intermediate itslength about which said member may oscillate and pivot, and templatemeans to control the pivotal movement thereof about said bearing duringits oscillatory movement.

4. A wheel dressingrdevice for gear grinders comprising in combination,an elongated member pivotally supported intermediate its length andadapted to be oscillated about its longitudinal a dressing tool at oneend of said mem ber, guiding means for said member adjacent its oppositeend whereby said tool during oscillation about its longitudinal axiswill have a limited swinging movement whereby said dressing tool willtraverse a symmetrical non-circular path, and an-anti friction bearingsupporting said member at an intermediate point about which said membermay pivot and oscillate.

5. A wheel dressing device for gear grinders comprising in combination,an elongated mamber pivotally supported intermediate its length andadapted to be oscillated about its longitudinal axis. an anti-frictionbearing having a spherical seat within which said member may pivot, adressing tool at one end of said member adjustable radially toward andfrom the axis of said member, and guiding means for said meanherincluding a template mounted adjacent its opposite end whereby said toolduring oscillation about its longitudinal axis will traverse asymmetrical curved path.

CLL KNOWLES. ART L. ER.

